Wireless communications devices such as the BlackBerry™ by Research in Motion Limited enable users to download map content from web-based data sources such as BlackBerry Maps™, Google Maps™ or Mapquest™. Downloaded map content is displayed on a small LCD display screen of the wireless communications device for viewing by the user. The user can pan up and down and side to side as well as zoom in or out. Due to the small display on the device and due to the limited over-the-air (OTA) bandwidth, there is a need to optimize the delivery and handling of the map data.
With the increasing availability of wireless communications devices having onboard Global Positioning System (GPS) receivers for providing location-based services (LBS), the efficient delivery and handling of map data is increasingly important.
One problem that arises with current map-rendering technologies occurs when attempting to render a label on a path that turns sharply. Conventional text-on-path algorithms will sometimes place the label where the path sharply turns, thereby resulting in a label that is not aesthetically pleasing and difficult to read.
A related problem arises when a label is rendered on a path that changes girth, for example when a four-lane path becomes a two-lane path. To render this path, a single path segment may be made to loop back on itself with a slight offset, to thus represent the wider four-lane path while a new vector path segment is rendered from the looping point onward to represent the narrower two-lane path. Since the path segments are rendered with thickness, the paths themselves appear fine onscreen. However, a label that is rendered along such a path, in the section containing the sharp turn is seldom aesthetically pleasing. Depending on the zoom level, the label itself can sometimes appear to be folded back on itself. Therefore, a technique for resolving sharp turns to enable efficient and aesthetically-pleasing labelling of paths having sharp turns thus remains highly desirable.
It will be noted that throughout the appended drawings, like features are identified by like reference numerals.